Energy intake effects at pasture on milk production and coagulation properties in girgentana goats with different as1-cn genotypes

Abstract

The aim of this study was to investigate whether proerties of milk from Girgentana goats of different as1-CN genotypes were affected by the energy intake at pasture. Thirty six goats were genotyped at as1-CN locus using several genomic techniques and milk protein analysis. Eight genotypes associted with low (FF, 2 goats), medium (AF, AN, BF, BN, 21 goats) and high (AA, AB, BB, 13 goats) as1-CN level have beed typed. The increase in energy intake (E) of goats from low (<1.8 Mcal/d) to medium (1.82.0 Mcal/d) and high level (>2.0 Mcal/d) corresponded to an increasing dry matter intake, diet CP percentage, milk yield and clotting parameters, and a reduction in milk fat. Depending on genotypes linked to increasign as1-CN, milk was higher in casein, curd firming time and curd firmness. Significant interaction between the effect of energy intake and as1-CN genotype was found for curd firming time and curd firmness, suggesting that changes in milk properties caused by feeding regimen could be different for goats differing in as1-CN genotype